Electrical plug with compressible means to retain contacts therein



Feb. 16, 1954 E. P. BRUS ELECTRICAL PLUG WITH COMPRESSIBLE MEANS TORETAIN CONTACTS THEREIN Filed Oct.

INVENTOR. E/W/Y 1 Bra/.5

BY {I I Array/w;-

Patented Feb. 16, 195 4 ELECTRICAL PLUG WITH COMPRESSIBLE MEANS TORETAIN CONTACTS THEREIN Emile P. Brus, Kansas City, Mo.

Application October 9, 1950, Serial No. 189,145

7 Claims.

This invention relates to electrical connections or fittings in thenature of terminals for extension cords or other cables havingelectrical conductors as a part thereof, the primary object being toprovide a sectional fitting so formed as to permit interconnecting andrelease in a simple, eficient and fully satisfactory manner.

It is the most important object of the present invention to provide anelectrical terminal that includes a hollow body for receiving a cable,together with an insert that closes one end of the body and engages theinner side walls thereof, the insert being of a compressible nature andthere being provided structure accessible exterior of the body and theplug for compressing the insert and wedge tightly against the innerwalls of the body.

A further object of this invention is the provision of an electricalfitting of the kind above set forth wherein the compressible member isalso adapted to receive one or more prongs or contactors that extendsinto the body and are adapted therein to connect with the conductor ofthe electrical cable or extension cord.

It is a further object of this invention to provide an electrical plugwherein the aforesaid compressible member is provided with a pair ofopposed elements that move toward and away from each other to impartcompression thereto, one of which is in turn adapted to hold thecontactor prongs in place within the body.

Other objects include the way in which the interengaging walls of thecompressible insert and the body are serrated to further assure againstrelative displacement; the way in which the insert is provided withprong-receiving openings that have lateral extensions to provide a tightconnection between interengaging prongs when the plug is placed in use;and the particular manner of forming the means for compressing theinsert so as to assure a rigid mounting therefor within the hollow body.

Many more minor objects will be made clear or become apparent as thefollowing specification progresses, reference being had to theaccompanying drawing, wherein:

Figure 1 is a substantially central, longitudinal cross-sectional viewthrough an electric plug made pursuant to one form of my presentinvention.

Fig. 2 is a cross-sectional view taken at right angles to Fig. 1 on lineII--II thereof.

Fig. 3 is a view similar to Fig. 1 showing a modified form of electricalplug embodying the present invention; and s Fig. 4 is a sectional viewtaken on line IV of Fig. 3 looking in the direction of the arrows.

As will hereinafter appear, the broad concepts of this invention areincluded both in the forms of my invention, and in the female-typeillustrated in Figs. 1 and 2 of the drawing there is provided a hollowbody of relatively rigid me.-

terial broadly designated by the numeral l0. It is to be preferred thatthe body ll) be relatively non-conducting of electricity and capable ofinstance, includes a pair of electrical conduc-- tors. it that areseparately insulated and also covered as a unit with an outermost layerof in-- sulation in the usual manner. That end of the:

v body It opposite to the cable-receiving opening i2, is initially fullyopen and adapted to receive a compressible member or insert l8 havingthe same general cross-sectional contour as the innermost face of bodyI0 adjacent the open end thereof.

Insert i8 is formed from any suitable flexible pliable material such asrubber or other rubberlike material and one end thereof is enlarged asat 20, presenting a continuous shoulder 22 that bears against theproximal end of body 10 when insert [8 is in place within the body I0. Acavity 24 preferably rectangular, is formed in the insert l3 at theoutermost end thereof adapted to receive a plate 26 having the sameconfiguration as cavity 24 and provided with a pair of openings 28 thatregister with substantially parallel openings formed in the plug I8.There is also provided a similar plate 32 that bears against theinnermost end of the insert l8 and having a pair of openings 34 thatregister with the openings 30 at the innermost ends thereof. The twoplates 26 and 32 are interconnected with the insert i8 therebetween bymeans of a bolt 36 receiving a tubular nut 38. Nut 38 is embeddedcentrally within the plate 32 and extends a short distance into the plugl8 as illustrated in the drawing.

The bolt 36 is provided with a kerf 40 at the outermost end thereof inthe usual manner for receiving a suitable tool and consequently, as bolt36 is rotated in one direction, the plates 26 and 32 will be movedtogether. As shown, the head of the bolt 36 is preferably embeddedpartially in plate 26 to present a smooth outermost surface in thecompleted plug. The openings 30 and 34 are each adapted to receive anelongated metallic contact blade or prong 42, each having a fasteningelement 44 within the body III for receiving a corresponding conductorl6, and releasably joining the same with the prong 42. That end of eachprong 42 opposite to the fastening element. is offset laterally as at 46in overlying relationship to the bottom wall of cavity 24 and thenceupwardly as at 48 for disposition within an opening 50 formed in theplate 26.

' ""When placed in use to receive a male plug 52,

the openings 28, 30 and 34 are adapted to receive the esponding ele trial prongs 54 of the plu 52 as illustrated in Fig. 1. It is of course.nec ssary that a good electrical contact be established and maintainedbetween the prongs -54 and 42 and accordingly, the insert I8 is providedwith an extension or ear 56 within each opening 38 re.- igectively inopposed relationship to the prong In assembling the parts just abovedescribed, it is preferable to first extend the cable [4 entirelythrough the body to a point exteriorly thereof opposite to opening l2where the conductors 16 can be easily and quicklyattached to the prongs42 by means of the elements 44. The prongs 42 are initially mounted inplace within the openings 30 of insert I8 and the plate 26 is thereuponinserted in the cavity 24 in overlying relationship to the offsetportions 46. Plates 26 and 32 are thereupon interconnected by means ofthe bolt 36 and the nut 38 and the entire assemblyincluding the cable H,the prongs 42, the insert [8 and the plates 26 and 32 are moved intoplace to the condition illustratedin Figs. 1 and 2.

The operator thereupon rotates the bolt 38 to draw the plates 26 and 32together. thereby automatically compressing that part of the insert l8between cavity 24 and the plate 32. Such compression upon the insert l8forces the outer face thereof below shoulder 22, tightly against theproximal innermost walls of the body 10. The frictional interengagementbetween the proximal faces of insert l8 and the body [0 holds the insertH! in place and such holding action is enhanced by the provision of anumber of serrations. or rlbgroove formations 58 ion the interengagingwalls of insert l8 and body ill. Such drawing together of the plates 26and 32 additionally serves to clamp the offset portions 46 of the prongs42 tightly in place between the plate 2 6. and the bot tom of cavity 24.

The acute angle between prongs 42 and the offset portion 45 thereof isless than 90 so that as portions 45 are forced tightly against insert i8by plate 26. prongs 42 will be forced apart. However, to further assurethat the prongs 42, will be maintained apart within body [0, earsv 56are providedin openings. 30,.

Another equally important feature of the plug made. possible by insert[8. lies in the way in which prongs 54 are held in lace thereby flatlyagainst prongs 42 and throughout the lengths thereof. After insert. l8commences to bear tightly against body to. by compression thereofthrough manipulation of bolt 3.6. openings 30- 01: insert l8 start toclose.

It is possible therefore, to reduce the size of openings 30- to a. pointwhere prongs 54. must be. inserted with force. Once in place the prongs54 are held tightly against. prongs, 42 along the. entire proximalsurfaces thereof, and by virtue of the tight frictional contact ofinsert it on the opposite face of prongs 54 the latter cannot be easilyremoved from openings 30. With pron s 42 and 54. thus held tightlytogether along a relatively long surface, good, non-arcing,. electricalcontact is presented.

If however, the plug 52 and the femaleterminal of Figs; 1 and- 2' areused together under-conditions where accidental separation is notlikely", and it is desired that the plugs be rendered more easilyseparated, then bolt 38' need only be turned to lessen the compressionon insert It. The frictlonal. contact of. the insert [8 on 9 1 1 8 itwill still hold the same in place but permit removal without difliculty.

There is presented therefore, an adjustment feature which may be easily,quickly and minutely regulated to suit the particular desires of theuser and the conditions under which the plug must operate.

In the form of my invention shown in Figs. 3 and 4 of the drawing, thereis illustrated a maletype of terminal connection embodying theprinciples above set forth and including a hollow body 69 of relativelyrigid material precisely as above explained with respect to body l0.Here again, body 60 is adapted to receive an electrical cable 62 andthere is provided an insert member of compressible material 64 adaptedfor fitting within the body 68. Body 60 is provided with an outwardlyfacing internal continuous shoulder 66 against which the insert 64 restswhen the same is in body 66.

A pair of electrical prongs or contactors 58 of metallic material passthrough the insert 64 and are held in substantial parallelism thereby.The lowermost end of each prong 68 is offset as shownin Fig. 3 andnormally rests upon an inward boss 19 formed within the body 60. Asabove set forth, the prongs 68 are provided with fastening elements 72within body 60 adapted to connect the conductors of cable 62. Theinterengaging walls of compressible'member 64 and body (id haveserrations i4 thereon in the same manner as at 58 in Figs. land 2 andcompression of the member 54 is through the medium of an externallythreaded body 76 passing through the insert 84 centrally thereof betweenthe prongs 68 and a nut member 18 threadably connected with the bolt 16.

The bolt It is provided with a head 80 presenting a shoulder 82 thatbears against the member 64 opposite to the nut element 18. As in thecase of the head of the bolt 76, the head 88 is partially embeddedwithin the insert '64.

The nut member 18 is formed from an initially fiat, preferably metallicelement that is bent in the form of a V as shown in Fig. 4 andperforated at the apex thereof for receiving the external threads ofbait lb. The compression member 64 may be initially provided with acavity in the normally innermost face'thereof for receiving the nutelement 18, but such is not necessary and when the bolt T8 is rotated tomove the element i8 toward the head 85, it will partially embed itselfwithin the insert 64 as shown in Figs. 3 and 4. In any event, as member84 is compressed by movement of the nut [8 toward the shoulder 82, the.insert 64 will be forced tightly against the proximal innerwalls of body76. Similarly, such compression of the member 64 will increase thefrictional holding action of the insert 64 upon the The. assembling ofthe device illustrated in Figs sand 4 is; substantially the same asabove outlined with respect to the female member of Figs. 1 and 2. Afterof. the parts are fully assembled exteriorly of the body 80, a pullingaction upon the cable 62 while insert 84 is pushed. into the body 60;will preliminarily assemblethe parts for the final step of compressinginsert 84 by means of the slotted bolt 15.

It is clear that the male terminal of Figs. 3 and 4 may be used with.the female plug shown in Figs. I and 2 and that when the prongs 68 areinserted in. openings 28, 30' and. 34, the inwardly proiecting tabs 56.will. yieldahly bear. against the prongs 68 and hold the same tightlyagainst the prongs 42.

Details of construction may be varied within the spirit of thisinvention and therefore, it is desired to be limited only by the scopeof the appended claims.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is 1. A terminal contact fitting for anelectric conductor cable, said fitting comprising a tubular body ofrigid material provided with a bore having a central axis; a compressiondevice of elastic material in the bore of said body, said device beingexpandable perpendicularly to said axis of the bore when the device iscompressed in a direction parallel to said axis; a contact elementcarried by the device and having means for electrically connecting theconductor of a cable thereto; and means carried by the device andseparate from the body for compressing said device to expand the sameinto tight gripping relationship with said body, said device beingfreely removable from the body when not compressed and being held in thebody only by said gripping relationship when compressed.

2. A terminal contact fitting for an electric conductor cable, saidfitting comprising a tubular body of rigid material provided with a borehavin a central axis; a compression device of elastic material in thebore of said body, said device being expandable perpendicularly to saidaxis of the bore when the device is compressed in a direction parallelto said axis; a contact element carried by the device and having meansfor electrically connecting the conductor of a cable thereto; and meanscarried by the device and separate from the body and including a pair ofmembers engaging opposite faces of the device and movable toward eachother for compressing said device to expand the same into tight grippingrelationship with said body, said device being freely removable from thebody when not compressed and being held in the body only by saidgripping relationship when compressed.

3. A terminal contact fitting for an electric conductor cable, saidfitting comprising a tubular body of rigid material provided with a borehaving a central axis; a compression device of elastic material in thebore of said body, said device being expandable perpendicularly to saidaxis of the bore when the device is compressed in a direction parallelto said axis; a contact element carried by the device and having meansfor electrically connecting the conductor of a cable thereto; and meanscarried by the device and including a pair of members engaging oppositefaces of the device, and structure extending through the device andjoining the members to move the same toward each other for compressingsaid device to expand the same into tight gripping relationship withsaid body, said device being freely removable from the body when notcompressed and being held in the body only by said gripping relationshipwhen compressed.

4. A terminal contact fitting for an electric conductor cable, saidfitting comprising a tubular body of rigid material; a compressiondevice in said body; an elongated contact element removably carried bythe device and having means for electrically connecting the conductor ofa cable thereto; and means including a pair of releasably interconnectedmembers engaging opposite faces of the device and movable toward eachother for compressing said device to force the same into tight grippingrelationship with said body, said contact element having a laterallyextending portion partially interposed between and in engagement withthe device and one of the members when the members are moved toward eachother to compress the device, whereby the contact element is held inplace on the device, said one member being removable from the devicewhen released from interconnection with the other member, whereby topermit removal of the element from the device.

5. A terminal contact fitting for an electric conductor cable, saidfitting comprising a tubular body of rigid material provided with a borehaving a central axis; a compression device of elastic material in thebore of said body, said device being expandable perpendicularly to saidaxis of the bore when the device is compressed in a di rection parallelto said axis; a contact element carried by the device and having meansfor electrically connecting the conductor of a cable thereto, therebeing serrated interengaging surfaces between the body and said device;and means carried by the device and separate from the body forcompressing the device to force said surfaces of the device into tightlygripping relationship against said surfaces of the body, said devicebeing freely removable from the body when not compressed and being heldin the body only by said gripping relationship when compressed.

6. A terminal contact fitting for an electric conductor cable, saidfitting comprising a tubular body of rigid material; a compressiondevice in said body; an elongated contact element carried by the deviceand having means for electrically connecting the conductor of a cablethereto; means for compressing said device to force the same into tightgripping relationship with said body, there being an elongated openingthrough the device for receiving said element; and a lateral projectionin the opening for yieldably holding the elongated contactor of acomplementary fitting in the opening and in tight lateral engagementwith said element, the lateral dimension of the opening being greaterthan the combined, corresponding lateral dimensions of the element andsaid contactor.

7. A terminal contact fitting for an electric conductor cable, saidfitting comprising a tubular body of rigid material; a compressiondevice in the body and having an opening therethrough; an elongatedcontact element in said opening and having means for electricallyconnecting the conductor of a cable thereto, said element being disposedin the opening for lateral engagement with the elongated contactor of acomplementary fitting; and means separate from the body for compressingsaid device to reduce the size of said Opening, whereby to force saidcontactor into tight, positive interengagement with the element.

EMILE P. BRUS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,286,919 Benjamin Dec. 10, 1918 1,376,068 Benjamin Apr. 26,1921 2,015,590 Cavanagh et al. Sept. 24, 1935 ,265,341 Borchert Dec. 9,1941 2,443,654 Else et a1. June 22, 1948 2,486,195 Munsey Oct. 25, 1949FOREIGN PATENTS Number Country Date 556,548 Great Britain u"...- Oct.11, 1943

